John Deere SPN 641 FMI 9 – Engine Control Module (ECM): Engine Variable Geometry Turbocharger Actuator #1 - Abnormal Update Rate / Loss of Communication

Communication has been lost between the Engine Control Module (ECM) and the Variable Geometry Turbocharger (VGT) Actuator over the J1939 CAN data link. To protect the engine from over-boosting, the ECM immediately commands the turbocharger vanes to default to a fully open, safe position, resulting in a red STOP ENGINE light, a severe drop in engine power, and sluggish machine performance.

• 5085E
• 5090E
• 5090EL
• 5100E
• 6.8L (6068) PowerTech engine
• 9.0L (6090) PowerTech engine
• 13.5L (6135) PowerTech engine
• 8410R
• 9410R
• 210G
• 250G
• 350G
• 624K

1. 1

   Check for associated codes: Troubleshoot low battery voltage codes (e.g., SPN 158) or CAN communication errors (e.g., SPN 2795) first, as low cranking voltage can cause communication drops.

2. 2

   Verify battery voltage: Ensure the system is receiving proper voltage (ideally >12.6V; anything under 12V can cause actuator dropouts).

3. 3

   Inspect the wiring harness: Check the wiring between the ECM and the VGT actuator for visible damage, corrosion, or open circuits.

4. 4

   Test the J1939 CAN Bus: Measure the resistance across the J1939 network with the battery disconnected. It should read 60 ohms. A reading of 120 ohms indicates a missing terminating resistor or a broken wire.

5. 5

   Verify power and ground: Confirm stable power and ground voltages directly at the VGT actuator harness connector.

1. 1

   Remove the Actuator

   Unbolt the faulty VGT actuator from the turbocharger bearing housing.

2. 2

   Inspect Mechanical Linkage

   Before installing a new actuator, manually move the turbocharger unison ring/linkage. Ensure the mechanical vanes move freely. If the vanes are seized due to carbon fouling, the turbocharger itself may require cleaning or replacement.

3. 3

   Install the New Actuator

   Mount the replacement VGT actuator to the turbocharger.

4. 4

   Perform VGT Calibration

   You must perform a VGT relearn/calibration procedure using a diagnostic tool (such as John Deere Service ADVISOR or a compatible aftermarket tool) before starting the engine to prevent an out-of-calibration fault.

5. 5

   Clear Codes and Test

   Clear the inactive codes from the ECM and test run the machine under load to verify boost pressure and ensure the code does not return.